Ao chegar à recepção, a recepcionista explicou o valor da diária e entregou a chave do quarto.

Ao chegar means upon arriving or when [someone] arrived.

This is a very common Portuguese structure:

ao + infinitive

It is used to express something that happens at the moment of another action or when doing something.

Examples:

• Ao entrar, ela sorriu. = Upon entering / When she entered, she smiled.
• Ao sair, apague a luz. = When leaving, turn off the light.

So in your sentence, Ao chegar à recepção sets the scene: when arriving at the reception/front desk.

Because à is the contraction of:

• a = the preposition to / at
• a = the feminine article the

So:

chegar a + a recepção = chegar à recepção

This is why the grave accent appears: à shows that two a sounds have merged.

Compare:

• chegar ao hotel = arrive at the hotel
• chegar à recepção = arrive at the reception/front desk

Good question. With the verb chegar, standard Portuguese normally uses the preposition a:

• chegar à recepção
• chegar ao hotel
• chegar ao aeroporto

So à recepção is the more standard choice after chegar.

That said, in everyday Brazilian Portuguese, many speakers also say chegar na recepção. This is very common in speech. But in more careful or formal Portuguese, chegar à recepção is usually preferred.

In this context, recepção means the reception area or front desk of a hotel.

Depending on context, it can refer to:

• the physical area near the entrance
• the reception desk itself
• the hotel’s reception service

In hotel language, English often says front desk, while Portuguese commonly says recepção.

In this sentence, yes, a recepcionista refers to a female receptionist because of the article a.

But the noun recepcionista itself usually has the same form for both masculine and feminine.

So you can have:

• o recepcionista = the male receptionist
• a recepcionista = the female receptionist

This is common with many profession words ending in -ista:

• o/a turista
• o/a dentista
• o/a jornalista

They are in the pretérito perfeito of Brazilian Portuguese, which usually corresponds to the simple past in English.

• explicou = explained
• entregou = handed over / gave
• chegou would be = arrived

This tense is used for completed actions in the past.

Here it shows a sequence of completed actions:

1. arrival at the reception
2. the receptionist explained the rate
3. the receptionist handed over the key

Because Portuguese does not need to repeat the subject if it stays the same.

So:

• a recepcionista explicou o valor da diária e entregou a chave do quarto

means:

• the receptionist explained the daily rate and handed over the room key

The subject of both verbs is still a recepcionista.

English also often does this:

• The receptionist explained the rate and handed over the key.

In hotel language, diária usually means the daily rate, nightly rate, or charge per day/night.

So o valor da diária is the amount of the room rate.

This word is very common in Brazilian Portuguese in travel and lodging contexts:

• Qual é o valor da diária? = What is the nightly rate?
• A diária inclui café da manhã? = Does the daily rate include breakfast?

Even though diária literally relates to something daily, in hotels it often refers to the price for one lodging period, typically one night.

Because o valor da diária is more explicit: it means the price of the daily/nightly rate.

Breakdown:

• valor = value, amount, price
• da diária = of the daily rate

So:

• explicou o valor da diária = explained the price/rate

You might also hear things like:

• informou a diária
• disse o valor da diária

But o valor da diária makes it especially clear that the speaker is talking about the amount charged.

Do is the contraction of:

• de = of
• o = the

So:

• de + o quarto = do quarto

Therefore:

• a chave do quarto = the key to the room or literally the key of the room

This kind of contraction is extremely common in Portuguese:

• de + a = da
• de + o = do
• de + as = das
• de + os = dos

Grammatically, this is an important point.

In Portuguese, a phrase like ao chegar... usually refers to the same subject as the main clause. So, strictly speaking, this sentence most naturally suggests that the receptionist is the one who arrived at the reception.

That can sound a little odd if the intended meaning is that the guest arrived there.

If you want to make the guest clearly the one arriving, Portuguese often makes that more explicit, for example:

• Quando cheguei à recepção, a recepcionista...
• Ao chegar à recepção, o hóspede...
• Quando o hóspede chegou à recepção...

So this is a useful sentence, but it also shows a structure where Portuguese learners should pay attention to who the subject is.

Portuguese uses definite articles much more often than English.

So where English might say:

• receptionist
• room key
• reception

Portuguese often says:

• a recepcionista
• a chave do quarto
• à recepção

This is completely normal. In many cases, leaving out the article would sound unnatural or change the meaning.

For English speakers, one of the big adjustments in Portuguese is getting used to articles appearing very frequently before nouns.

Yes. Portuguese allows some flexibility in word order.

For example, you could also say:

• A recepcionista explicou o valor da diária e entregou a chave do quarto ao chegar à recepção.

But the original version:

• Ao chegar à recepção, a recepcionista explicou o valor da diária e entregou a chave do quarto.

sounds more natural if you want to start with the time/situation frame: upon arriving at the reception.

Beginning with Ao chegar... is a very common way to introduce what happened next.